Ever increasing manufacturing tolerances have required improvements in manufacturing techniques. One such improvement is the projection of laser templates onto a work surface for directing a manufacturing process. This technique has allowed for manufacturing products at tolerances not previously achievable. However, restrictions to existing technology have limited a broader use of laser-projected images in industrial applications. For example, projecting a template onto a three-dimensional surface has proven difficult due to the inability to rapidly identify the three-dimensional work surface and to focus the laser beam onto the three-dimensional work surface in a precise manner, all while operating in a manufacturing environment.
Accurate projection of a template pattern onto a three dimensional work surface requires precise calibration of the relative position between the work surface and the laser projector. Initially, this has been achieved by locating reflective targets on the work surface, measuring the target coordinates relative to a three-dimensional coordinate system of the work surface, and then locating the position of the projector relative to the work surface using a process of calculating the position of the projector where known laser projections to the targets pass through known three-dimensional target coordinates. Periodically, the template scanning sequence is stopped and a target is located to check for variation in the projected pattern location due to a change in the position of the projector relative to the tool, or to compensate for other factors such as drift due to temperature variations in the environment, for example. When variation is detected, the targets are relocated, a new template scanning sequence is calculated, and is again transmitted by the laser projector.
The time associated with scanning target positions using a conventional laser projector has proven to be slow and inefficient. As a result, evaluating projection drift has only been performed intermittently and correction of the projected patterns has resulted in noticeable interruptions of the visible pattern template.
Therefore, it would be desirable to develop a more efficient method of locating a three-dimensional work surface relative to a laser projector to improve precision and quality of a laser template projection.